Interactive television (“TV” hereafter) enables television viewers to both receive broadcast signals so they can be displayed on their own TV screen and also to send signals back to the broadcast source that are associated in some way with the program being shown. This two-way transmission capability is highly desirable to enhance viewing enjoyment as well as for other purposes involving educational, marketing, surveying, and other activities. Interactivity is possible with cable because of its two-way transmission capacity. However, programs supplied via cable involve a limited audience and require specialized equipment which incurs additional costs both to the broadcasters and the viewers. Interactive television is not available for viewers who receive the programs via an antenna or through satellite transmission because these have only a one-way capability.